The cost of computing and networking technologies have fallen to the point where computing and networking capabilities can be built into the design of many electronic devices in the home, the office and public places. The combination of inexpensive and reliable shared networking media with a new class of small computing devices has created an opportunity for new functionality based mainly on the connectivity among these devices. This connectivity can be used to remotely control devices, to move digital data in the form of audio, video and still images between devices, to share information among devices and with the unconstrained World Wide Web of the Internet (hereafter “Web”) and to exchange structured and secure digital data to support things like electronic commerce. The connectivity also enables many new applications for computing devices, such as proximity-based usage scenarios where devices interact based at least in part on geographical or other notions of proximity. A prevalent feature of these connectivity scenarios is to provide remote access and control of connected devices and services from another device with user interface capabilities (e.g., a universal remote controller, handheld computer or digital assistant, cell phones, and the like). These developments are occurring at the same time as more people are becoming connected to the Internet and as connectivity solutions are falling in price and increasing in speed. These trends are leading towards a world of ubiquitous and pervasive networked computing, where all types of devices are able to effortlessly and seamlessly interconnect and interact.
In the above ubiquitous and pervasive networked computing scenarios, the devices desirably can interoperate on an ad hoc peer-to-peer networking connectivity basis. Such a peer networking connectivity model enables any networked device to initiate a communication with any other networked device, without having established a prior relationship or maintaining a persistent relationship between the devices. This peer networking connectivity also allows multiple devices to establish one or more connections with a single device, and it allows for a device to be capable of both initiating and accepting connections to/from other devices.
The prevalent model for device connectivity, however, has been that of host-peripheral connectivity, typified by the personal computer and its many peripheral devices (e.g., data storage drives, user input devices, displays, printers, scanners, etc.) connected via various buses (e.g., PCI, VESA, AGP, Microchannel, ISA, EISA, USB), ports (e.g., serial, parallel), and connectors (e.g., PS/2 connector). This host-peripheral connectivity model is characterized in that the host and peripherals typically have persistent relationships and stable configurations. This persistent relationship is created, by example, through a set-up and configuration process through which appropriate driver software is installed by a user or administrator onto the host for use in controlling the peripheral, and updating the host's configuration to include peripheral device settings. Such persistent configured relationships with a user installation/configuration experience are generally inappropriate to the ubiquitous and pervasive computing environment where portable and mobile devices desirably can instantly connect and interact with other computing devices in their environment without having established prior or persistent relationships.
More specifically, two common computing networks where many of these small, network-capable computing devices are expected to be used include the home and small office. Such networks are commonly not actively managed by experienced administrators. In fact, due to the lack of networking experience of a large majority of the users of these networks, lengthy, complex and/or involved user installation and setup experiences pose a significant impediment to adoption and penetration of such networks and devices into homes and small offices.
Further, the establishment of persistent relationships with other devices in the configuration of these small, network-capable computing devices is inappropriate to many usage scenarios. For example, portable computing devices (such as a handheld computer or digital assistant, cell phones, and the like) may be used to access information (such as transportation departure/arrival times, store locations, etc.) from other devices on networks in public places (such as malls and airports). Not only would a user installation/configuration experience upon each such use pose an inconvenience, but the establishment of persistent configuration information poses configuration management issues and consumes device resources. As another example, devices (such as printers, scanners, monitors and etc.) on an office or home network may interact with many portable computing devices (such as the laptops, cameras, and other equipment of the mobile professional) that are introduced into its network. Again, in device connectivity models requiring establishing persistent device relationship configurations, such one-time and occasional relationships between these devices would results in configuration instability requiring management and maintenance of ever-changing persistent device configurations. Due to the time and cost (or lack of) active administration of these devices, any requirement to manage and maintain changing persistent device configurations on networked devices is undesirable.
Accordingly, there is a need for a device connectivity model that supports ad hoc peer networking among computing devices with preferably zero user installation or configuration experience and without persistent device configuration.
In accordance with a technology described herein, a universal plug and play (UPnP) device makes itself known and available for communication with other entities on a network through a set of processes—discovery, description, control, eventing, and presentation (herein also termed “self-bootstrapping”). Following discovery of a UPnP device, an entity can learn more about the device and its capabilities, or interact with the device, by retrieving the device's description from a URL provided by the device in an initial discovery message.
The description is expressed in XML and includes vendor-specific manufacturer information like the model name and number, serial number, manufacturer name, URLs to vendor-specific Web sites, etc. The description also includes a list of any embedded devices or services, as well as URLs for control, eventing, and presentation.
The description is written by a vendor and is usually based on a standard device template produced by a UPnP forum working committee. The template is derived from a template language that utilizes standard XML constructions. The template language includes a first set of elements to describe the UPnP device and a second set of elements to describe any services supported by the device. The template language is written using an XML-based syntax that organizes and structures the first and second sets of elements.
Additional features and advantages will be made apparent from the following detailed description of the illustrated embodiment, which proceeds with reference to the accompanying drawings.